Process for the production of sulphates



Patented Jul 18,1933

, oouwAY, memos GmsEv r'ALi) AN ERICHY s m,er mimxromiommamm;

A 003203515101 91 NEW xonx' GERMANY, 'ASSIGNOBS'TO AMERICAN Lurerconfona'rro vgor 0321:,- N

Q I QEWU T were a fioDrdvvlng, Application filed February 24, 1931 S erial No; September 13 ;i1929.

' n We have filed applications for-patent in Germany, September "13, 1929, v in Switzer land, December 16, 1930, in the Netherlands, January 2,1931, i'nNNor-way, December 29,

1930, in Russia, January 2, 1931, Sweden, December 20, 1930, in" Italy, December 26,

1930, in Austria, December 9, 1930, and in Czechoslovakia, January 1931.

This invention relates to a'process production of sulphates. a

for

In our earller patent Serial Number 438,894 ).We have protected a proc css'for the production ofsulphates, in which" 1 gaseousmixtures of sulphur" dioxide and oxygen-tithe latter being advantageouslyin excess.andpreferably those in]; which the substantially exceed" 51%, are introduced, in

j ofnozzles orany other (suchj as mechani:

cal-)- means-into an "aqueous"v medium care bemg takento-neutralize the vacidgformed n the-reaction mi'xture by mean'svbi'; basiofsubstances, such as ammonia, 'copperoxide, zinc oxide or the like, and preferably bythe con tinuous ,introductionof the basic substances,

in such quantity i'ntjothe reaction liquid,

during the introduction of the gaseous mixturef containing sulphuftlioXide, thatthe rek action of said liquid is'maint'ained as nearly neutral as, possible during the oxidat on process'. According to one method otcarrying out the process,rthereaction-can bevvholly' [or partially perfbrinedat elevatedltempera'a ture, and,-iffdesired, suchfa inanner that the sulphate formed at the elevated temperature is allowed toaccum'ulate'in the solution -to anextent exceeding-the limit of saturation at ordinary temperature, the solution being then freed from the exeess of sulphate by cooling, whereupon thefoperation'can be cbntinued With the residualsolution, Alter natively,.the oxidation process canbecarried on, at elevated ;temperature-, until the accumulation of sulphate exceeds the limit of saturation in the hot liquid; the sulphate which is thereafter continuously formed and deposited 7 being? continuously or i interihit tently removed from, thereaction liquid. i L

{Accordi g to another embodiment, and e's-f pecially-in operating-with concentrated solu tions, the; oxidationmay be effected pres= ence 11 ty-small quantities of v Water-soluble.

order to ';-retain the copp'ei y in. solutiom as f cuprousjchloride. I

Ina ur her m diment-aiui wdtsslge 1 @COI'dlIlg to our earli ripa ent,"insteadoi ins trodu cingibothtthefoxygen (or gas eontain- 111g same) needed iforj the; oxidation and the sulphur dioxide. (Qinitheforni'of its mixture),

' ina finelydivided-state',-.into theaqueousfme f f 0 3 the 'l'bxyg l tor; 'gals,- such lair, F? containing same) maygbe introd-uced, ,infa- 4 finelyrdivided'state,into.the aqueousmediuin, V thelatter containing sulphurousacid orsalts q fof same' such as. neutraljor {and acidsodis urnjor; ammonium snlphitee'sor-into which 9 sulphur-dioxide (or agaseous mixture con; taining same) is introduced ixilanygconven ientfinanner during theii troductipn ofthe gas containing oxygeii, Alternatively, -s'ul f vphurous-acid or; a salt ofsamwniaybe-introduced', in the form; ofia solutiorfor' as-a solid i I salt, intofsaid} aqueous medium 7 i i i This manner of 'operatingjofi'ei'fs tage, when the sulphur dioxide is'introdu c'ed in the gaseous form, thati the said gas no f longer need be carefullyjfreedj from fluefj dust'in,view ofthe risk" ofzelogging-the V poresoff the feed'devices and' alsothat cork eS On-e th m a Pa t 9f the-emp s by'sulphur dioxide isobviated,whilstflnfgen v al; y" a 1--vb um;mega eft brought to the requisitepressure fir obtain ing fineness of division -tor, example b'y-fforc ing the same transmission. surfaces can be reducedin size,

for the same total efliciency.

a When operating in this manner, instead of 1 introducing only the gas,containing oxygen and free from sulphurdioxide, into theaqueous medium in a finely'divided state, one may also introduce a portion-of the sulphur diox- 1 ide-ina 'finelydivided state, for example'in added to theaqueous solutiomin a solid,disv f solved or suspended'form, before or/ and during the, introduction of'the oxygen, or gases admixture with air, the remainder being in-l troduced as gas,-orin liquid, solid or differ ent forms, in'adinixture-With air if desired, by anyother convenient means. 7 s 7 A'cording tothe presentv invention in the oxidation of sulphurous acid, in an aqueous medium .in anyeconvenient frmif desired,

in the condition of'an acidsulphite, or introduced into the aqueous medium, in, any 'con-' venient form, during, the oxidation process by the pass'age of finely divided oxygen, or

gases containing same, through said aqueous medium, the basic substances employed for combining. with a portion atleast of the acids produced, may consist of abasic phosphate, such as a, tertiary or secondary alkali phosphate. "These phosphates, which may be I containing same, are convertedintophos- Iphates of'lower basicityby the-free sulphuric acid. formed.

*In this manner therefore, according to'the kind and quantity ofthe phosphates introduced, there are obtained, in addition to'the corresponding sulphates, the corresponding secondary or primary phosphates, namely in fthe ease of trialkali phosphate the correspending dior'monosalkali phosphate, and

in thecase of dialkali phosphatezthe corresponding mono-alkali phosphate. Owingto their greater solubility atllow temperatures, the alkali phosphates formed in this manner can beeasily separated from the simultanepassed therethrough, together with an excess of air (which'may be wholly or partially centration,

ou sly formed" sulphates by crystallization.

Moreover, 'by starting, for example, with a concentrated phosphate solution, SO can be ially introduced into 120000. of wate'rat l (1, and at the sametime a mixture of air and- 5% ofiSO is blown in through a microporous plate[ The. solution contains25 grams of phosphorus, 80 grams of SO and 8 grams of sO per litre. On cooling to 0 0., 300 grams of Glaubers saltcontaining 0.1% of P, separate outincrystal form. I

about 0.1 of 'P, crystallize out. After a further addition of 1000 grams 500 grams of phosphate'are" added to the A mother liquor in a similar manner, andafter the mixtureof S0 and air has again been blown through a further 300 grams of Glaubers salt crystallize out. When the saturation limit for NaH PO has been reached,"this salt-canbe isolated, for example by concentrating the solution. I 'Ewa/mple 2 l .1000 grass :0i 7 dis'odiuni "phosphate, r Na HPO 12 aq.,- are gradually introduced into 1200 cc.'of water at 80 (1, andv atth'e same time, a mixture ofjair and 5% of S0 Y is blown in, in a finelydivided state, through the microporousfalse bottom o fjthe vessel, until the calculated acidity for monosodium sulphatehas'beenattained'. On cooling to 0 C; 350grams "of Glaiibers salt,.containing' Na HPO 12 aq. tothe mother liquor sepa rated from the Glaubers salt, 80; and air are again passed through in similar manner. 7 By cooling the resulting solution, another 400 grams of Glaubers salt crystals are obtained.

The final liquor separated froin these crystals contains 99 'gramsof P and' ltgramsof S0 per litre. After-the 'solution'has been correspondingly concentrated, monosodium phosphate, NaHgPO H O crystallizes out.

sam les 750' grams of tripotassium phosphate, K POA, (containing 10.7% of P) are gradually introduced into 1200 cc. of water, whilst at 'thesame time a mixture ofair and 5% of S0 is blown in, until the acidityborre- .sponding' to d-ipotassium phosphate has been attained. On cooling to 0 0., 150 grams of potassium sulphate crystallize. out.

'. Another'7 50 grams of tripotassium phate are added to the mother liquor freed air and S0 being again blown in 'as'before.

1 from the potassium sulphate, the mixture of After cooling'the' solution to 0? G., there are siumsulphate-and a mother liquor containing 90 grams ofP and 20 grams of S0 per-litre. V V On-concentration, and recrystallization of the finally obtained a furtherfQOO grams of potas first crystalline deposit 'of;dipotas'siuin ph0s-' phate', K HPO (which still contains about phate can be obtained a pure state. 0 I .i lE pze I 360 of K PO (containing 10.7 of

10% of potassium sulphate), the said phosf P) dissolvedin 400 cc. of water, are gradu ally introduced into-800 ccof water, gas

containing 5% of SO being introduced at thesame time. After the acidity correspond O ing to the salt KH PO has been attained, air

is passed through for a furtherfZ hours, until all the sulphite has'been oxidized to sulphate; About 98% of theSO gas is utilized. On

"cooling to 136 grams of K SO (with The reaction 0.2%,,0f P) crystallize out. cycle is repeated with the mother liquor until a solution containing 65 rams of P (as KH POQ and g'rams of; 0 per litre is obtained. On the solution being concentrated to half'the original volume, 400 grams of salt an aqueous solution, into 'Whichsulphuifous acid, 111 any convenient-form and manner, s

(containing 90% of KH PO per-litre crystallize out and can be freed fromthe remain= derof the potassium sulphate by recrystallization from water.

We claim 1. Process for the production of alkali metal sulphates and phosphates, which comprises introducing very finely divided air into we ter-soluble basic metal phosphate.

3. Process for. the production of alkali metal sulphate and alkali metal phosphates 'vvhichfcomprises introducing a very finely l divided gas,consisti ng at'least in part of free oxygen, into an aqueous solution, into'vvhich sulphurous acid, in any convenient form and manner, is introduced as Well as a trialkali phosphate. i

4., Process divided gas, consisting at least in partr of free oxygeminto an "aqueous s0lution, into which sulphurous acid, in anyfconvenient I form and manner, is introduced as. wellas a trialkali phosphate in "sufficient quantity the tribasic phosphate.

for the conversion of into the dibasic salt.

7'0 for the." production of alkali l metal sulphate and alkali'metal phosphates Which comprises introducing a very finely.

5. Process for the productionfliof metal sulphate and alkali metal phosphates which comprises introducing a very: finely divided gas, consisting at least'in partof free conversion of the dibasic phosphate into the monobasic salt. i 1

oxygen, intoan aqueous solution,intoyvhich, sulphurous' acid, in any: convenient form and manner, is introduced as Well .as a dibasic a alkali phosphate in suflicient quantity for the '7 C WAY, BARON vbn I IIRSEwA LDQi land 

